Computer data storage systems that employ disk drives have conventionally used a single, electrically inductive head for reading and writing data to and from the disk. More recently, it has been known to use one or more magnetoresistive (MR) head elements for reading and an inductive head element for writing. Obviously, regardless of the type of head element employed, the quality and reliability of such head components are critical to data storage systems. As such, read/write heads and associated circuitry may be subject to specific electrical testing during the manufacturing process to identify and weed out defective units, as well as improve the manufacturing and handling process.
Prior methods of testing read/write heads have been to physically probe the heads with test contacts after manufacture to determine whether they have the proper electrical characteristics. For example, probe testing identifies improper head element resistance, determines electrical continuity, open circuits, short circuits, and can identify electrostatic discharge (ESD) damage. Often, however, testing is only performed after completion of the manufacturing process and after a failure has occurred because probe testing such fragile and electrically sensitive components during the manufacturing process is difficult and time consuming.
On a conventional inductive, single read/write head, only two wires are associated with the head for electrical connection and testing purposes. However, in more recent data storage systems employing dual MR read heads and/or multiple heads in head stack assemblies (HSA), a significant number of more wires and electrical connections exist and thus the difficulty of testing the heads and the care with which testing must occur is compounded. Probe testing such systems can easily cause head element damage or peripheral circuitry damage.
On the one hand, testing must be reliable and efficient to avoid excessive testing costs and to improve manufacturing production flows, product quality, and product reliability. On the other hand, it is extremely important that testing be performed carefully to avoid sensitive head damage. However, conventional methods of testing read/write head elements and associated circuitry has not afforded a means for cost effective testing during the manufacturing process. Accordingly, objects of the present invention are to provide an improved system and method for testing disk drive read/write head elements and connecting circuitry.